The present invention relates to a tooth filling material formed of a porous sintered gold compact body to be used for filling cavities and which are solidified under the action of ultrasound.
A number of metallic filling substances are known in the field of preservation dentistry such as e.g. amalgams and cast alloys in the form of inlays or filler gold. The filling of dental cavities with filler gold is one of the oldest tooth filling methods. Chemically pure gold in the form of gold foil, gold sponge or gold powder is used for these gold plug fillings.
Gold plug fillings prepared from pure gold are highly regarded with respect to durability, esthetics and corrosion resistance. However, significant disadvantages of gold plug fillings are the technically complicated and time-consuming preparation of the cavity and the positioning of the filling, which also requires great skill. Thus, a very meticulous working of the cavity is necessary at first with undercuts and a roughening of the cavity walls which can not be performed automatically. Both procedures are absolute prerequisites for a sufficient adhesion of the gold in the cavity. Moreover, the cavity must be absolutely free of moisture during the gold filling procedure. This applies not only to the saliva flow but also to the respiratory air of the patient.
This necessitates the use of so-called cofferdam foils, which is likewise time-consuming and occasionally very unpleasant for the patient. In addition, the material of the gold plug filling must be annealed in a very clean alcohol flame immediately before being placed into the cavity in order that all impurities on the surface are removed and a cohesive bond between the individual gold particles is achieved. The ability of the gold to be cold-welded, the basis of gold plug filling, is sharply reduced by a contamination of the surface, especially by liquid or moisture films.
German Patent No. 30 42 008 teaches a gold filling method in which a porous sintered compact or a skein of gauze wire, preferably of gold, is introduced into the cavity together with a plastic or liquid organic binder which solidifies in a temperature range from 15 to 40.degree. C. Binders such as methyl methacrylate or other plastics or dental cements customarily employed in dentistry are mentioned. The resulting composition is then manipulated with manual tamping devices into the cavity and then solidified. The sintered gold compacts formed thereby exhibit a pore volume of 58 to 66%. However, surfaces can not be produced with this method that are free of all objectionable factors. In addition, these surfaces are not purely metallic but still contain the organic binder, usually methacrylates.
U.S. Pat. No. 1,040,972 teaches a plastic gold material consisting of gold fibers or gold sponge impregnated with a wax which softens under heat and hardens during cooling, which material can also be used to prepare dental fillings. Here as well, surfaces cannot be produced that are completely satisfactory since the wax remains in the dental filling.
German Patent No. 34 03 779 teaches a tooth filling material to be placed in cavities and solidified under the action of ultrasound which consists of platelet-shaped gold powder and polyethylene glycol in amounts of 0.5 to 5% by weight. The presence of an organic binder in the dental filling represents a disadvantageous in this patented development.